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Viral defenders

THE bacteria that kill nine out of ten patients with cystic fibrosis may in
future by kept at bay by viruses extracted from sewage. These viruses, called
bacteriophages, infect and kill strains of Pseudomonas aeruginosa that
are resistant to imipenem, one of the front-line antibiotics used to fight the
bacteria.

Zemphira Alavidze and her colleagues at the University of Maryland School of
Medicine in Baltimore isolated three strains of bacteriophage from the sewage
system at the university’s medical centre. Applied to laboratory cultures, they
killed 80 per cent of 162 strains of antibiotic-resistant P. aeruginosa.

The next step is to test the bacteriophages in animals. If these experiments
are successful, the team hopes to start clinical trials. Provided the phage
works, cystic fibrosis patients could benefit the most: the disease causes
sticky mucus to build up in the lungs, so that sufferers are susceptible to
infection by P. aeruginosa and other bacteria.

Alavidze also directs a team at the Eliava Institute of Bacteriophage
Research at Tbilisi in Georgia, which has a huge bank of bacteriophages that are
effective against a range of common bacteria.

But Sankar Adhya of the US
National Institutes of Health near Washington DC, who is also working on the
bacteriophage approach (New Scientist, Science, 27 April 1996, p 16),
is more cautious. His own animal research, also presented in Chicago, suggests
that bacteriophages lose their potency unless given within hours of infection.
“Rapid diagnosis is critical,” he says.